Springless, tilting plates clock driven by two oval gears



Nov. 30, 1965 E. CAPPELLARI SPRINGLESS, TILTING PLATES CLOCK DRIVEN BYTWO OVAL GEARS Filed March 5, 1964 4 Sheets-Sheet l 4 Sheets-Sheet 2 E.CAPPELLARI Nov. 30, 1965 SPRINGLESS, TILTING PLATES CLOCK DRIVEN BY TWOOVAL GEARS Filed March 5, 1964 mvme Nov. 30, 1965 E. CAPPELLARISPRINGLESS, TILTING PLATES CLOCK DRIVEN BY TWO OVAL GEARS Filed March 5,1964 4 Sheets-Sheet 5 Nov. 30, 1965 E. CAPPELLARI 3,220,174

SPRINGLESS, TILTING PLATES CLOCK DRIVEN BY TWO OVAL GEARS Filed March 5,1964 4 Sheets-Sheet 4 United States Patent SPRINGLESS, TILTING PLATESCLOCK DRIVEN BY TWO OVAL GEARS Elio Cappellari, Milan, Italy, assignorto Enrico Boselli S.p.A., Milan, Italy, an Italian joint-stock companyFiled Mar. 3, 1964, Ser. No. 349,082 Claims priority, application Italy,Mar. 6, 1963, 4,731/63, Patent 689,108 6 Claims. (Cl. 582) Thisinvention relates to a springless clock, having tilting plates hinged onhorizontally rotary drums and carrying the hours and minutesindications, and driven by two oval gears.

As already well known, such clocks of the prior art are comprisive oftilting plates hinged on vertically revolving drums, where said platesare guided and driven by spiral springs, being the minute units drumdriven by quick tripping systems, whereby the plates are subjected todynamic stresses, while the drive of decade drum is derived from thedrive of unit drum by means of cams or of cams and of a kinematismconsisting of a lever, a pawl and a driving spring, and the drive ofhours drum is derived from the main drive mechanism either directly orthrough a similar system comprisive of cams and of a kinematismconsisting of a lever, pawl, ratchet wheel and driving spring. In saidclocks, the hours are indicated by number larger than those of theminutes, whereby the readings can be made only from a distance smallerthan that from which the hours would be clearly visible.

The above and further drawbacks are obviated by this invention, thatconsists in a tilting plates type clock, characterized in that theplates are hinged on horizontal drums, and are tilted by two side pins,acting against the end of each plate, near to rotation center thereof,pushing same plate beyond the vertical, whereby it is tilted withoutneed of springs; that the minute units drum is driven by a motor, thatcauses the quick indexing thereof through two oval gears which arepivoted on two opposite foci; that the drive of minute decades drum isderived from the unit minutes drum through conventional gears and aone-tooth gear; that the drive of hour units drum is derived from thatof minute decades drum in a manner similar to the previously describedone, without need to have recourse, neither directly nor indirectly tomain driving mechanism; that the size of hour numbers is similar to thatof minute numbers, whereby both indications can be read from the samedistance.

The above and further objects and advantages of the invention will bebetter appreciated from a consideration of the following description ofa preferred embodiment form thereof, taken with the accompanyingdrawings, being both description and drawings given only as a notrestrictive example. In same drawings:

FIG. 1 is a front view of the clock according to the invention.

FIG. 2 is a rear view of the clock dial, with tilting plates, supportsand driving mechanism.

FIG. 3 is a cross-section of clock, taken on the line A-B of FIG. 2.

FIG. 4 is an enlarged partial section, taken on the line C-D of FIG. 2.

FIG. 5 shows a plate supporting roller, with two plates only, that arehinged on supporting disks.

FIG. 6 shows a structural detail of a tilting plate.

FIG. 7 is a partial section taken on the line EF of FIG. 2.

FIG. FIG. 2.

FIG. FIG. 3.

8 is a partial section taken on the line G-H of 9 is a partial section,taken on the line I-L of Patented Nov. 30, 1965 'ice FIG. 10 is apartial section, taken on the line M-N of FIG. 3.

FIG. 11 is a partial section taken on the line OP of FIG. 3.

FIG. 12 is the diagram showing the variation of speed of driven ovalgear, as function of the time.

FIG. 13 shows the driving device of the minute units drum, powered by aDC. small motor, that is fed by current pulses which are sent eachminute from a centralized timing plant. 7

FIG. 14 is the connection diagram of the driving arrangement as shown inthe FIG. .13, by assuming that unidirectional pulses be sent eachminute, and that the DC. motor be of the series-wound type.

FIG. 15 is the connexion diagram of the driving arrangement as shown inthe FIG. 13, by assuming that polarized pulses be sent each minute, andthat the DC. motor be of the shunt-wound type.

FIG. 16 is the connection diagram of the driving arrangement as shown inthe FIG. 13, by assuming that polarized pulses be sent each minute, andthat the DC. motor be of the series-wound type.

FIG. 17 shows the driving mechanism, consisting of a balance movement,for the minute plate drum.

Referring now in particular to FIGS. 1 and 2 of accompanying drawings,the clock according to this invention essentially consists of apanel-dial 1, that serves also as support for the tilting plate drums 2,3, 4, and that shows three windows in which the tilting platessuccessively appear; of the driving mechanism 5; of the means by whichthe drums are connected with one another; of a protective transparentcasing 6 for the dial, and of a case 7 wherein all mechanisms as fittedon the dial rear side are enclosed.

The tilting plate drum 2, as shown in FIGS. 4 and 5, consists of a shaft8, whereon two disks 9 and 10 are keyed, being each of such disks formedwith 10 holes, located near their outer edge, and spaced 36 deg. fromone another.

As shown in the FIG. 6, each plate of drum 2 is made of a flat metal orplastic sheet, and consists of a middle section 11, of two oppositelydirected side pins 12 and 13, extending into the holes 9 and 10, andacting as journal pins; of two stepped sections 14 and 15, that extendfrom the two vertical sides of the plate 16 and 17, for an amount Aslightly larger than the length of small pins 18, that are secured onthe disks 9 and 10. The pins -18 are provided, i.e. in a number equal tothat of the holes as formed on the disks 9 and 10, and to that ofplates, being same pins located in the positions as shown in the FIG. 4,i.e. along a circle having a diameter slightly larger than that alongwhich the holes wherein the plates are journalled, are formed, and againat a center-to-center spacing of 36 deg, but staggered of ab. 10 deg. inanticlockwise direction, in respect of latter holes.

The pins 18 are fitted, in both disks 9 and 10, in the same locations inrespect of the holes of related disk; however, they are directed towardsthe plate. As shown in the FIGS. 4 and 5, each pair of opposite pins 20and 21, acting on the same plate 22, are designed to exert a thrustagainst the plate stepped sections 14 and 15, and since latter sectionsare located below the center of rotation of plate, this latter is causedto rotate in the direction of the arrow.

All other pins 18 of both disks 9 and 10, by acting on the steppedsections 14 and 15 of related plates, that momentarily are on the upperhalf of drum, will keep them in their proper positions, therebypreventing that the rear end of a plate, e.g. the end 23, may strikeagainst the surface of the preceding plate.

The lip 24, that extends from the panel-dial l, is intended to preventall possible swinging motions of the 81 plate 25 that is tilted aftereach indexing of drum, and to act as an extension of same plate 25,directed down wardly in an approximately vertical direction.

At each indexing of drum 2 around its axis 8, the plate 22, due tothrust exerted by the rungs 2t and 21, will lift the pawl 27, which endis formed with a notch 28, having two sides inclined at ab. 90 deg, andthat is loose fitted on the pin 29.

After the drum 2 has been indexed for ab. 3 deg, the plate 22 will bereleased from the pawl 27, and since it has been turned, in themeantime, beyond the vertical line, a tilting for ab. 180 deg. thereoftakes place, due to the force of gravity, whereby it takes the place ofplate 25. Simultaneously, due to the action of same rungs 18, and offurther indexing of drum 2, the plate 26 will be also advanced in thesame direction of the arrow, thus lifting again the pawl 27, owing tothe downward crooked shape thereof. When the position shown by brokenlines 30 is taken by the plate 26, i.e. after it has been lifted abovethe lowest end of pawl 27, same plate will be moved toward its verticalposition, due to the action of the inclined plane, of notch 28 and ofthe weight of pawl, and more precisely it will be moved into the upperapex of said notch 28. The plate can freely perform such small rotationin the forward direction, since such motion takes place in the directionas allowed by the pins 18.

Finally, it must be observed that the plate can be freely tilted for ab.180 deg, as stated above, because the length of pins 18 is smaller thanthe already stated level A.

A special feature of the above described type of plates, and of thearrangement thereof on horizontal drums, consists in the fact that sameplates are tilted by the more force of gravity, and that the platesupporting disks can be suitably masked on the front side of dial.

The above described operation of drum 2, having ten tilting plates thatare numbered from to 9 inclusive, is referred to that of minute figures.

Such operation is similar to that of minute decade drum 3, that consistsof 12 plates, numbered from 0 to inclusive for two successive times, aswell as to that of hour drum 4, carrying 12 or 24 plates, thatrespectively are numbered from 1 to 12 inclusive, or from 0 to 23inclusive, and that therefore are not again described, for brevityssake.

The minute unit drum 2 is driven by the shaft 31, that is powered by asynchron motor 5 at the speed of one complete turn per minute.

The oval gear 33 (FIGS. 2, 3, 8) fast with the shaft 31 by means of thepressure screw 32, is in mesh with a further oval gear 34, keyed on theshaft 35, that is supported by the bearing 36, and whereon the one toothgear is also keyed.

Said one tooth gear 37 gets engaged at each revolution with a tooth ofgear 38 that is keyed on the shaft 8, and remains engaged therewith for36 deg. and since teeth are formed on said gear 38, an angular rotationof 36 deg. will be also accomplished by the shaft 8. Consequently, owingto what is stated above, a new pair of plates, carrying the numbersubsequent to preceding one, according to already described progressiveand cyclic numbering, shall appear in the window of dial 1.

Should a uniform rotary motion be imparted to shaft 35, then the time asrequired to have the drum 2 indexed by of turn would be of 60 sec/10:6sec. which is too long.

Conversely, by the provision of the two oval gears 33 and 34, a speedvariable according to diagram shown in FIG. 12 is imparted to shaft 35whereby, by adjusting the one tooth gear 37 in such a manner as to getengaged with the gear 38 when the shaft 35 is turning at its max.angular speed, then the time as required to have the drum 2 indexed by Aof turn, becomes 6 sec/4:15 seconds, which is wholly admissible, withthe added advantage that such indexing of drum 2and also of all otherdrums, as stated hereinafter-takes place under the form 4. of anapproximately uniform motion, and without submitting the plates tonoticeable dynamic stresses.

To prevent that the drum 2 may be turned backward, owing to the weightof plates, after the one tooth gear 37 has been disengaged from the gear38, the outer contour of disk lltl is formed with it saw tooth notches,with which gets engaged the pawl 39 (FIG. 7), that is kept against thedisk by its own weight, and that is p1votally fitted on the threaded pin40. For the same reason, as many saw tooth notches as the plates are,are cut on the outer contour of the two disks 41 and 42 of rnmutedecades and of hours, and the pawls 43 and 44 are designed to getengaged therewith, thereby preventlng the related plate drums fromturning backward.

As stated before, at each indexing of drum, and angular motion of 36deg. is imparted to gear 45 which, as shown in FIGS. 3 and 5, is keyedon the shaft 8. Such motion is transmitted, in the ratio 1: 1, to gear46, wh1ch which the former gear is engaged, and that is secured by thepressure screw 47, to the shaft 48, which is laid on the bearing 49, andwhereon the one tooth gear is also keyed.

At each whole turn of shaft 8 of the minute unit drum 2, that is laid onbearings 49 and 51, one whole turn s also accomplished by the one toothgear 50, which 15 brought in the position as shown in the FIG. 10 whenthe plate carrying the number 9 appears in the plate WlIldow (see FIG.4).

A gear 54, having 12 teeth, is keyed on the shaft 52 of the minutedecade drum 3, which is laid in the bearings 45 and 53.

At the next indexing by 36 deg. of drum 2, the one tooth gear 50 getsengaged with the gear 54, thereby causing the shaft 52 of minute decadedrum 3 to be turned by 30 deg. and reaching then the position as shownwith broken lines in the FIG. 10.

As a consequence thereof, the number 0 Wlll appear on the plates 22 and25 of drum 2, while a decade number increased by one unit appears on theplates of drum 3.

The gear 55, also keyed on the shaft 52 of drum 3, gets engaged, in a1:1 transmission ratio, with the gear 56, that is secured, by means ofthe pressure screw 57, on the shaft 58, which is laid in the bronze bush59 carried by the support 53, and whereon the two teeth gear is keyed.The two teeth of said gear 60 are spaced by deg. from one another.

A gear 63, having 12 teeth, is keyed on the shaft 61 of hour drum 4,that is laid on the bearings 53 and 62. One tooth of gear 60 getsengaged with the former gear at each half turn of shaft 58.

When the number 59 appears on the minute plates, then the two teeth gear60 will be in position as shown in FIG. 11.

At the next indexing by 36 deg. of shaft 8, the shaft 52 will perform anangular motion of 30 deg., the two teeth gear will be brought in theposition as shown with broken lines in FIG. 11, while an angular motion,also of 30 deg. is imparted to shaft 61 of hour drum 4. Thus, in pointof fact, the above-stated angular motion by 36 deg. of shaft 8 willresult in the indexing by one pitch of all the three drums; moreprecisely, two 0 will appear on the plates of the two minute drums,while the indication of next hour shall appear on the plates of hourdrum.

The two pressure screws 47 and 57 allow not only a mutual adjustment ofdrums, but also the taking-up of gear lost motions.

When 24 plates are carried by the hour drum 4, for the indication ofhours from 0 to 23 inclusive, then the gear 63 shall have 24 teeth, andat each half turn of shaft 58, the shaft 61 will perform an angularmotion of 15 deg.

In the clock as hereinbefore described, the prime mover is representedby the synchronous small motor, by which the shaft 31 is driven at thespeed of one turn per minute.

However, recourse may be made, as prime mover, also to a clockwork 64(see FIG. 7) of the already well known type, and that is therefore onlydiagrammatically shown in the accompanying drawing, without describingit. By such a clock work, the shaft 31 will be driven also at the speedof one revolution per minute, and with a uniform motion.

The prime mover may also be a rotary armature polarized relay by which,as consequence of the polarized electrical pulses sent by a centralizedtiming plant, the shaft 8 of the minute unit drum 2 is turned by ofturn, at the sixtieth of each minute.

Such type of relay is already well known, whereby a description thereofcan be dispensed with.

Finallyand in particular to the purpose of preventing the plates frombeing subjected to dynamic stressesthe prime mover may be represented bya D.C. small motor 65, as shown in the perspective view of FIG. 13, andthat at each pulse sent at each minute by a centralized tim ing plant,will impart, by the worm 66 and the worm wheel 67, a 180 deg. rotarymotion to shaft 35, that is laid in the bronze bush 36 of support 51,and whereon the cam 68 and the two teeth gear 69 are keyed. In theposition as shown in FIG. 13, the micro-diversing switch 70 has beentripped in its contact position 71, due to the fact that the largerdiameter cam track section, having an amplitude of 180 deg, is enteredinto action while the shaft 35 was being turned.

In such a position, the two teeth of the gear 69 are not engaged withthe gear 38 that is keyed on the shaft 8 of minute drum, as clearlyshown in the FIG. 13.

When unidirectional current pulses are sent from the centralized timingplant (see FIG. 14), a reversing relay 72, of the already known type,will provide for the conversion thereof into reversed polarity pulses,as shown in the two additional diagrams of FIG. 14, where theunidirectional pulses fed to relay 72, and the pulses as delivered bysame relay are shown.

When the DC. motor 63 is of the series-wound type, it will rotate alwaysin the same direction, whatever the polarity of voltage fed to theirterminals may be, and due account is taken thereof in the connexiondiagrams of FIGS. 14 and 16.

By assuming that the pulses as sent from the centralized timing plant atthe sixtieth second of each minute, have a duration of 2 seconds, andthat one second is required to have the shaft 35 turned by 180 deg, apulse sent by the relay 72, and having a polarity as marked in bracketsin the FIG. 14, will pass through the diode 73, thereby applying avoltage to fractional motor 65, whereby the shaft 35 shall be moved byhalf a utrn. After such rotary motion, the arm of micro-diversing switch70 will find itself on the smaller diameter track portion of cam 68,thus changing same switch over the contact 74. In the latter position,though the pulse as sent by the centralized timing plant is acting forone more second, the motor will stop itself, because the current isswitched off by the diode 75.

A tooth of the two teeth gear 69, that is turned by 180 deg. along withthe shaft 35, gets engaged for 36 deg. with the gear 38, whereby thislatter is turned by of revolution.

A new pulse, as reversed by the relay 72, will cause the shaft 8 of theminute unit drum, to be indexed by 36 deg., whereby the circuit isbrought back in the conditions as shown in the drawing, and theoperation of clock is further repeated in the already described manner.

If polarized pulses are sent by the centralized timing plant, and if theDC. motor is of the series-wound type, then the diagram of FIG. 16 isvalid, being latter diagram, from the reversing relay 72 onward, similarto diagram of FIG. 14.

Finally, if polarized pulses are again sent by the centralized timingplant, being however the DC. motor of the shunt-wound type, i.e. whereinthe sense of rotation is changed with the polarity, then the diagram ofFIG.

is valid, wherein unlike the preceding ones, a Groetz bridge rectifier76 has been added, in order to have a fixed polarity voltage fed to saidmotor.

While a preferred embodiment form of the invention has been describedand shown with some detail, it is to be understood that the descriptionis for the purpose of illustration only, and is not definitive of thelimits of the inventive idea. The right is reserved to make such changesin the details of construction and arrangement of parts, as will fallwithin the purview of the attached claims.

What I claim is:

1. In a horological device: a frame structure including a vertical frontwall portion having apertures therein, first, second and third drumassemblies supported for rotation about a common horizontal axis behindsaid wall portion for displaying time indications through the aperturesthereof, each one of said assemblies comprising a shaft supported forrotation around said horizontal axis, two spaced parallel plates securedto said shaft, and a plurality of blades of essentially rectangularshape positioned between said plates, each blade having time indicatingindicia thereon and being freely swingably connected to said plates foroscillation about a horizontal axis located adjacent one edge of suchblade, the blades being evenly arranged on the plates with the axes ofoscillation thereof forming a circle, whereby upon rotation of saidassemblies the time indicating indicia sequentially appear at theapertures of said front wall portion as said blades are caused tosequentially drop from an up-turned vertical position to a down-turnedvertical position, the blades related to said assemblies beingcorrelated respectively to minutes, tens of minutes and hours, atime-controlled source of rotary motion having an output shaft driven ata rate of speed of one revolution per minute, a first elliptical gearwheel secured to said output shaft, a second elliptical gear wheel inmesh with said first gear wheel and driven thereby in rotation at onerevolution per minute at sequentially accelerated and deceleratedspeeds, and first gear means connecting said second elliptical gearwheel to the shaft of said first assembly for imparting thereto afractional rotation as said second elliptical gear wheel is acceleratedto cause one blade of said first assembly to drop from said up-turnedposition to said downturned position, second gear means connecting theshaft of said first assembly to the shaft of said second assembly forimparting to said second assembly a fractional rotation to cause a bladeof said second assembly to drop from its up-turned position to itsdown-turned position as said first assembly has completed onerevolution, and third gear means connecting the shaft of said secondassembly to the shaft of said third assembly for imparting to said thirdassembly a fractional rotation to cause a blade of said third assemblyto drop from its up-turned to its down-turned position as said secondassembly has completed a given rotation, whereby each fractionalrotation of each assembly is imparted by a temporarily acceleratedmotion through the shaft of said first assembly.

2. The combination of claim 1, wherein the second assembly has tenswingable blades evenly arranged and having impressed faces sequentiallyimpressed to display figures 0 to 5 and then 0 to 5 again, said thirdgear means connecting the shaft of said second assembly to the shaft ofsaid third assembly to fractionally rotate said third assembly as thesecond assembly has completed half a revolution.

3. The combination of claim 1, wherein said blades include oppositelyprotruding portions defining the axis of oscillation of said blades andprotruding abutments on said portions, said plates having a plurality ofholes in which said first protruding portions are rotatablyaccommodated, and inwardly protruding pins positioned on said plates toabut and engage said abutments for urging each blade to said up-turnedposition as said blade is upwardly rotated upon rotation of theassociated assembly.

4. The combination of claim 1, comprising a shaft secured to said secondelliptical gear wheel and driven at cyclically accelerated anddecelerated speeds by said first elliptical gear, said first gear meanscomprising a onetooth gear secured to said shaft and rotatingconcurrently with said second elliptical wheel, and a ten-teeth gearmeshing with said one-tooth gear and secured to the said first assembly,said one-tooth gear being oriented in angular phased relation with saidelliptical gears to engage said ten-teeth gear as said second ellipticalgear is rotated at its greatest speed whereby said shaft of said firstassembly is caused to rotate 36 as said second elliptical gear hascompleted one revolution, such that said first assembly and the secondassembly driven by said first assembly are driven only when therotational speed of the second elliptical gear is at its greatest in thecyclical rotary motion thereof.

5. The combination of claim 1, wherein said aperture defines a spacecoplanarly to two of said blades as in said up-turned and in saiddown-turned vertical position thereof, a pawl oscillatably supportedabove said aperture and having a down-turned notch releasably engagingthe up turned blades one by one to maintain such blades in saidup-turned position until a further fractional motion of the assemblylowers said blade from engagement in said o notch, causing said blade tofall to its said down-turned vertical position.

6. The combination of claim 5, comprising means integrally formed insaid wall portion at the lower edge of said aperture and positioned fortemporarily retaining a number of fallen down-turned blades thereon tomaintain the last fallen blade in said vertical down-turned position,until a further fractional motion of the assembly pulls one of saidfallen blades off said abutment to permit the sequential and concurrentaccommodation of the newly fallen blade in said position.

References Cited by the Examiner UNITED STATES PATENTS 715,776 12/1902Fitch 58-126 724,460 4/1903 Fitch 58-125 2,687,003 8/1954 Junghans58-125 FOREIGN PATENTS 849,199 11/1939 France. 334,374 1/ 1959Switzerland.

LEO SMILOW, Primary Examiner.

1. IN A HOROLOGICAL DEVICE: A FRAM ESTRUCTURE INCLUDING A VERTICAL FRONTWALL PORTION HAVING APERTURES THEREIN, FIRST SECOND AND THIRD DRUMASSEMBLIES SUPPRORTED FOR ROTATION ABOUT A COMMON HORIZONTAL AXIS BEHINDSAID WALL PORTION FOR DISPLAYING TIME INDICATIONS THROUGH THE APPERTURESTHEREOF, EACH ONE OF SAID ASSEMBLIES COMPRISING A SHAFT SUPPORTED FORROTATION AROUND SAID HORIZONTAL AXIS, TWO SPACED PARALLED PLATES SECUREDTO SAID SHAFT, AND A PLURALITY OF BLADES OF ESSENTIALLY RECTANGULARSHAPE POSITIONED BETWEEN SAID PLATES, EACH BLADE HAVING TIME INDICATINGINDICIA THEREON AND BEING FREELOY SWINGABLY CONNECTED TO SAID PLATES FOROSCILLATION ABOUT A HORIZONTAL AXIS LOCATION ADJACENT ONE EDGE OF SUCHBLADE, THE BLADES BEING EVENLY ARRANGED ON THE PLATES WITH THE AXIS OFOSCILLATION THEREOF FORMING A CIRCLE, WHEREBY UPON ROTATION OF SAIDASSEMBLIES THE TIME INDICATING INDICASEQUENTIALLY APPEAR AT THEAPERTURES OF SAID FRONT WALL PORTION AS SAID BLADES ARE CAUSED TOSEQUENTIALLY DROP FROM AN UP-TURNED VERTICAL POSITION TO A DOWN-TURNEDVERTICAL POSITION, THE BLADES RELATED TO SAID ASSEMBLIES BEINGCORRELATED RESPECTIVELY THE MINUTES, TENS OF MINUTES AND HOURS, ATIME-CONTROLLED SOURCE OF ROTARY MOTION HAVING AN OUTPUT SHAFT DRIVEN ATA RATE OF SPEED OF ONE REVOLUTION PER MINUTE, A FIRST ELLIPTICAL GEARWHEEL SECURED TO SAID OUTPUT SHAFT A SECOND ELLIPTICAL GEAR WHEEL INMESH WITH SAID FIRST GEAR WHEEL AND DRIVEN THEREBY IN ROTATION AT ONEREVOLUTION PER MINUTE AT SEQUENTIALLY ACCELERATED AND DECELERATEDSPEEDS, AND FIRST GEAR MEANS CONNECTING SAID SECOND ELLIPTICAL GEARWHHEL TO THE SHAFT OF SAID FIRST ASSEMBLY FOR IMPARTING THERTO AFRACTIONAL ROTATION AS SAID SECOND ELLIPTICAL GEAR WHEEL IS ACCELERATEDTO CAUSE ONE BLADE OF SAID FIRST ASSEMBLY TO DROP FROM SAID UP-TURNEDPOSITON TO SAID SHAFT TURNED POSITION, SECOND GEAR MEANS CONNECTING THESHAFT OF SAID FIRST ASSEMBLOY TO THE SHAFT OF SAID SECOND ASSEMBLY FORIMPARTING TO SAID SECOND ASSEMBLY A FRACTIONAL ROTATION TO CAUSE A BLADEOF SAID SECOND ASSEMBLY TO DROP FROM ITS UP-TURNED POSITION TO ITSDOWN-TURNED POSITION AS SAID FIRST ASSEMBLY HAS COMPLETED ONEREVOLUTION, AND THIRD GEAR MEANS CONNECTING THE SHAFT OF SAID SECONDASSEMBLY TO THE SHAFT OF SID THIRD ASSEMBLY FOR IMPARTING TO SAID THIRDASSEMBLY A FRACTIONAL ROTATION TO CAUSE A BLADE OF SAID THIRD ASSEMBLYTO DROP FROM ITS UP-TURNED TO ITS DOWN-TURNED POSTION AS SADI SECONDASSEMBLY HAS COMPLETED A GIVEN ROTATION, WHEREBY EACH FRACTIONALROTATION OF EACH ASSEMBLY IS IMPARTED BY A TEMPORARILY ACCELERATEDMOTION THROUGH THE SHAFT OF SAID FIRST ASSEMBLY.